(1) Field of the Invention
The present invention relates to a shade device to be mounted on a vehicle such as an automobile.
(2) Description of Related Art
DE 102007016154 A1 discloses a configuration of a roller blind for a window. According to this configuration, a free edge of the roller blind is connected to a pull rod, and the pull rod is guided by a support rod during extraction and retraction of the roller blind. The roller blind of DE 102007016154 A1 is biased in the extracting direction by force of a spiral spring in a spring motor.
The spring motor disclosed in DE 102007016154 A1 generates the extracting force for extracting the roller blind by restoring force of the spiral spring returning from a state wound with a reduced diameter to an original state. In this case, when the roller blind is extracted by the spring motor, the extraction force is large at a start of movement of the roller blind (i.e., a rotation initial stage of the spring motor). However, the extraction force decreases as extraction of the roller blind develops (i.e., a rotation late stage of the spring motor). For allowing extraction of the roller blind by the force of the spring motor even after large extraction of the roller blind, the spring motor to be used is required to generate large extraction force in a state of large extraction of the roller blind. When such a spring motor is used, however, biasing force of the spring motor becomes excessively large at the start of movement of the roller blind. As a result, the completely extracted roller blind extracted with large force comes into violent contact with an upper edge portion of a window. This contact may generate large noise and give discomfort to an occupant of a vehicle.
Accordingly, an object of the present invention is to realize extraction of a shade with appropriate force.